I NEED A POSITIVE COMMENT BASED IN THIS ARGUMENT..BETWEEN 150-200 WORDS.

 

 

Random sampling is a method in which all members of a group (population or universe) have an equal and independent chance of being selected. It’s one of the most popular types of probability sampling. In this technique, each member of the population has an equal chance of being selected as a subject. There are many methods to proceed with random sampling: the most primitive and mechanical one would be lottery method. Another way would be to let a computer do a random selection from the population (Liu, H., Sadygov, R. G., & Yates, J. R. 2004).

 The importance of this method includes:
i. It is easy and accurate method of representation as no easier method exists to extract a research sample from a larger population.
ii. It is considered as a fair way of selecting a sample from a given population since every member is given equal opportunities of being selected.
iii. Yields a sample that is representative to the group being studied.
iv. It only needs a minimum knowledge of the study group or population in advance.
v. It is free from errors in classification.
vi. It is totally free from bias and prejudice.

Random sampling also inherent various drawbacks which are:
1) The process may cost the individual a substantial amount of time and capital as it takes time to gather the information from various sources.
2) When a sample set of the larger population is not inclusive enough, sample selection bias may occur.
3) The selection of sample becomes impossible if the units or items are widely dispersed.
4) It cannot be employed where the units of the population are heterogeneous in nature.
5)  It may be impossible to contract the cases which are very widely dispersed.
6) It lacks the use of available knowledge concerning the population.

 

  In conclusion, the methods limitations can be prevented by, keeping in mind that the list of the population must be complete and up-to-date to ensure effective sampling. A random sampling requires a complete list of all members of the target population so that the sample is a real representation of the larger group. Finally, no matter how large the population is, if it is not based on the random method the results will not represent the population that the researchers wants to draw conclusions about. To avoid this ensure that you first check to see how they were selected , look for the random sample, dig further into fine print to see the sample that was actually collected and use the preceding definition to verify that the sample was, in fact, selected randomly( Riffe, D., Aust, C. F., & Lacy, S. R. 1993).

References
Liu, H., Sadygov, R. G., & Yates, J. R. (2004). A model for random sampling and estimation of  relative protein abundance in shotgun proteomics. Analytical chemistry, 76(14), 4193- 4201.

Riffe, D., Aust, C. F., & Lacy, S. R. (1993). The effectiveness of random, consecutive day and  constructed week sampling in newspaper content analysis. Journalism & Mass  Communication Quarterly, 70(1), 133-139.

 

1.      For the following statements, state the null and alternative hypotheses and identify which represents the claim. Determine when a type I or type II error occurs for a hypothesis test of the claim. Determine whether the hypothesis test is left-tailed, right-tailed, or two-tailed, and explain your reasoning. Explain how you should interpret a decision that rejects the null hypothesis. Explain how you would interpret a decision that fails to reject the null hypothesis.

a.      It is reported that the number of residents in Wisconsin who support plans to recall the governor is 48%.

b.      An Amish bakery store states that the average shelf life of their fresh baked goods is seven days.

c.      A soda manufacturer states that the average number of calories in the regular soda is less than 150 calories per serving.

The census figures show that the average income for a family in a rural region is approximately $34,860 per year. A random sample has a mean income of $33,566 per year, with a standard deviation of $1,245. At a sig. level of .0.01 is there enough evidence to reject the claim? Explain.

The employees in a grocery store are handing out samples of a certain brand of Pizza. This is the pizza company’s way of determining whether people like the brand of pizza and would prefer it over other brands. Do you think this type of sampling is representative of the population? Explain. Identify possible flaws or biases in this study

 

 

 

 

A researcher claims that taking a protein supplement as part of a weight gainer program for athletes will help them gain muscle weight. The weights in pounds of 10 athletes are listed below before and after using the protein supplement.   At a sig. of .05 can you conclude that this supplement helps the athletes gain weight?

 

 

Athlete	1	2	3	4	5	6	7	8	9	10
Weight Before	196	220	187	184	206	198	174	176	182	174
Weight After	198	224	185	185	213	196	178	180	175	174

1. For the network shown here, calculate the following:
1. Mean duration (µ)
2. Variance (σ_µ²)
3. Standard Deviation (σ_µ)

Probability that the network can be completed in 50 days or less.

 

2.

1.     The following information concerns progress at day 40 of an Internet marketing project. Determine if the project is in control based on time and cost to date.  If not, what is the cost overage or underage?

 

 

Activity	Duration	Budget	Actual Cost	% Complete
1-2	10	300	250	100.00
2-3	8	400	450	100.00
2-4	12	350	380	100.00
4-3	0	0	0
3-5	18	405	400	70.00
5-6	16	450	——-	0.00

 

A Project has just completed the 87^th item in its action plan. It was scheduled to have spent $168,000 at this point in the plan but has actually spent only $156,000. The foreman estimates that the value of the work actually finished is about $162, 000. What are the spending and schedule variances for the project? What are the SPI and CPI?

1.

When examining differences between proportions, it is appropriate to use which approach to defining the standard error of the sampling distribution?

A) both approaches are appropriate

B) the pooled-variances approach

C) neither approach is appropriate

D) the separate-variances approach

2. 10. A police department is implementing a new initiative in different high crime areas throughout the city—they will be assigning an officer to walk the area for one month. I have been asked to assess whether the strategy was effective in reducing calls for police service. I am interesting in the number of calls for service in a specific location before an officer was assigned to walk the area and after an officer was assigned to walk the area. What type of statistical technique would I use?

A) T-test for independent samples

B) F-test

C) T-test for dependent samples

D) There is no way to make the comparison.

E) Chi-square test of independence

3.

Typically, when using a t-test to compare means, what level of measurement is the independent variable?

A) Ordinal

B) Interval

C) Nominal

D) Ratio

 

4.

When the samples are relatively large or are evenly divided, the estimates of the standard error using the pooled-variances and separate-variances approaches will be _____.

A) Exactly equal

B) Similar

C) Statistically significant

D) Dissimilar

5.

Why can we use a normal sampling distribution to test hypotheses involving proportions?

A) because the mean and standard deviation are appropriate statistics to use with proportions

B) because as N increases the sampling distribution of a proportion approximates a normal curve

C) because proportions are ratio-level measures

D) all the answers given

6.

I am getting ready to calculate and independent sample t-test. I have assumed homoscedasticity. What am I assuming?

A) That I fail to reject the null hypothesis.

B) That the standard deviations of the two groups are not equal

C) That the standard deviations of the two groups are equal

D) That I reject the null hypothesis.

 

7.

A two-sample t-test…

A) compares two samples to one another

B) compares a sample to a known population

C) compares apples and oranges

D) compares a sample to an unknown population

8.

I have completed an F-test and rejected the null hypothesis. What does this mean?

A) I can reject the null hypothesis of no difference between two independent means.

B) I can assume homoscedasticity.

C) I cannot assume homoscedasticity.

D) I can use the pooled variance estimate of t.

9.

The null hypothesis for a difference of means test is generally what?

A) that there are no means

B) that the means are the same

C) that the means are not the same

D) none of the choices given

10.

The assumption that population distributions have equal standard deviations is known as what?

A) homoscedasticity

B) multicolinearity

C) discordancy

D) heteroscedasticity

11.

One of the requirements of the two-sample t-test is that the samples examined be what?

A) proportionate

B) independent

C) equal

D) representative

 

12.

To perform a t-test comparing means, what “minimal” level of measurement must your dependent variable be?

A) Interval

B) Nominal

C) Ratio

D) Ordinal

13.

A “dependent samples T Test” is used for what type of two samples? (Select all that apply)

A) Control and treatment

B) Matched

C) Independent

14.

The pooled-variance approach to calculating the standard error assumes that the population distributions have _____ variances.

A) large

B) small

C) unequal

D) equal

1. Assume that an event A contains 10 observations and event B contains 15 observations. If the intersection of events A and B contains exactly 3 observations, how many observations are in the union of these two events?

A. 28

B. 10

C. 22

D. 0

 

2. Let event A = rolling a 1 on a die, and let event B = rolling an even number on a die. Which of the following is correct concerning these two events?

A. On a Venn diagram, event B would contain event A.

B. Events A and B are mutually exclusive.

C. On a Venn diagram, event A would overlap event B.

D. Events A and B are exhaustive.

 

3. From an ordinary deck of 52 playing cards, one is selected at random. What is the probability that the selected card is either an ace, a queen, or a three?

A. 0.3

B. 0.25

C. 0.0769

D. 0.2308

 

4. Which of the following is correct concerning the Poisson distribution?

A. The mean is usually larger than the variance.

B. The event being studied is restricted to a given span of time, space, or distance.

C. Each event being studied must be statistically dependent on the previous event.

D. The mean is usually smaller than the variance.

 

5. A breeder records probabilities for two variables in a population of animals using the two-way table given here. Let A be the event “shaggy and brown-haired.” Compute P(Ac).

 Brown-haired BlondShort-haired 0.06 0.23

Shaggy 0.51 0.20

A. 0.36

B. 0.49

C. 0.77

D. 0.51

 

6. A credit card company decides to study the frequency with which its cardholders charge for items from a certain chain of retail stores. The data values collected in the study appear to be normally distributed with a mean of 25 charged purchases and a standard deviation of 2 charged purchases. Out of the total number of cardholders, about how many would you expect are charging 27 or more purchases in this study?

A. 47.8%

B. 94.8%

C. 68.3%

D. 15.9%

 

7. In the binomial probability distribution, p stands for the

A. probability of failure in any given trial.

B. number of trials.

C. number of successes.

D. probability of success in any given trial.

 

8. The Burger Bin fast-food restaurant sells a mean of 24 burgers an hour and its burger sales are normally distributed. The standard deviation is 3.061. What is the probability that the Burger Bin will sell 12 to 18 burgers in an hour?

A. 0.342

B. 0.475

C. 0.136

D. 0.239

 

9. Consider an experiment that results in a positive outcome with probability 0.38 and a negative outcome with probability 0.62. Create a new experiment consisting of repeating the original experiment 3 times. Assume each repetition is independent of the others. What is the probability of three successes?

A. 1.14

B. 0.238

C. 0.762

D. 0.055

 

10. An apartment complex has two activating devices in each fire detector. One is smoke-activated and has a probability of .98 of sounding an alarm when it should. The second is a heat-sensitive activator and has a probability of .95 of operating when it should. Each activator operates independently of the other. Presume a fire starts near a detector. What is the probability that both activating devices will work properly?

A. 0.049

B. 0.9895C. 0.931

D. 0.965

 

11. Each football game begins with a coin toss in the presence of the captains from the two opposing teams. (The winner of the toss has the choice of goals or of kicking or receiving the first kickoff.) A particular football team is scheduled to play 10 games this season. Let x = the number of coin tosses that the team captain wins during the season. Using the appropriate table in your textbook, solve for P(4 ≤ x ≤8).

A. 0.817

B. 0.377

C. 0.246

D. 0.171

 

12. The probability of an offender having a speeding ticket is 35%, having a parking ticket is 44%, having both is 12%. What is the probability of an offender having either a speeding ticket or a parking ticket or both?

A. 67%

B. 79%

C. 55%

D. 91%

 

13. For each car entering the drive-through of a fast-food restaurant, x = the number of occupants. In this study, x is a

A. joint probability.

B. discrete random variable.

C. continuous quantitative variable.

D. dependent event.

 

14. A basketball team at a university is composed of ten players. The team is made up of players who play the position of either guard, forward, or center. Four of the ten are guards, four are forwards, and two are centers. The numbers that the players wear on their shirts are 1, 2, 3, and 4 for the guards; 5, 6, 7, and 8 for the forwards; and 9 and 10 for the centers. The starting five are numbered 1, 3, 5, 7, and 9. Let a 

player be selected at random from the ten. The events are defined as follows: 

Let A be the event that the player selected has a number from 1 to 8. 

 

Let B be the event that the player selected is a guard. 

 

Let C be the event that the player selected is a forward. 

 

Let D be the event that the player selected is a starter. 

 

Let E be the event that the player selected is a center. 

Calculate P(C).

A. 0.20

B. 0.40C. 0.50

D. 0.80

 

 Protestant Catholic Jewish Other 

Democrat 0.35 0.10 0.03 0.02 

Republican 0.27 0.09 0.02 0.01 

Independent 0.05 0.03 0.02 0.01

15. The table above gives the probabilities of combinations of religion and political parties in a city in the United States. What is the probability that a randomly selected person will be a Protestant and at the same time be a Democrat or a Republican?

A. 0.89

B. 0.62

C. 0.67

D. 0.35

 

16. A breeder records probabilities for two variables in a population of animals using the two-way table given here. Given that an animal is brown-haired, what is the probability that it’s short-haired?

 Brown-haired Blond

Short-haired 0.06 0.23 

Shaggy 0.51 0.20 

A. 0.0306

B. 0.222

C. 0.105

D. 0.06

 

17. Which of the following is a discrete random variable?

A. The weight of football players in the NFL

B. The time required to drive from Dallas to Denver

C. The average daily consumption of water in a household

D. The number of three-point shots completed in a college basketball game

 

18. Find the z-score that determines that the area to the right of z is 0.8264.

A. 0.94

B. –1.36

C. –0.94

D. 1.36

 

19. Tornadoes for January in Kansas average 3.2 per month. What is the probability that, next January, Kansas will experience exactly two tornadoes?End of exam 

A. 0.4076

B. 0.2087

C. 0.2226

D. 0.1304

 

20. If event A and event B are mutually exclusive, P(A or B) =

A. P(A) + P(B).

B. P(A) + P(B) – P(A and B).

C. P(A) – P(B).

D. P(A + B).